Outreach screen

ABSTRACT

A pair of spaced upright masts each support at opposite sides two opposed guides providing respective tracks for travellers. The travellers are independently vertically moveable along their respective tracks by cables wound around motor-driven pulleys at their upper ends. A gas strut inside the upper end portion of each track is engaged by the corresponding traveller when the associated screen approaches and passes through a horizontal plane. The compressive resistance offered by the strut when engaged by the traveller increases the load on the traveller. This increase in load compensates for a reduction in the downward thrust exerted on the traveller by the weight of the associated screen as it passes through the horizontal plane. Instability in the positioning of the screen is thus avoided so that the two screens can be stably positioned in parallel sloping but spaced planes. Thus the area protected from above by the screens can be safely maximized.

FIELD OF THE INVENTION

THIS INVENTION relates to an up-and-over screen assembly, and is morespecifically, although not exclusively concerned with such an assemblyhaving a screen that can be moved between a first position at which itstands almost vertically, or vertically alongside the lower portion ofspaced upright tracks, and an elevated position at which the screenextends approximately at right angles to the tracks to protect an areabeneath the screen from ambient conditions such as rain, hail or directsunlight. The screen is moved between its two positions by lifting atraveller or travellers along respective upright tracks which may beprovided by vertical guides or other means. The screen is guided duringits movement between its two operating positions by one or more rigidlinks. The upper end of each link is pivoted at a location fixed withreference to the upper end of the track so as to turn about a horizontalfirst common axis, and the link slopes downwards to a second location atwhich it is attached to the screen to turn about a second pivotal axiswhich is parallel to the first pivotal axis. One example of such anup-and-over screen assembly is described in detail and illustrated inthe specification of my co-pending international published patentapplication No. WO 03/040490 A1 hereby inserted by way of reference.

The advantage of an up-and-over screen is that the area that is shieldedfrom above by the screen, is not physically traversed during movement ofthe screen between its two positions. Thus, for example if the screen isbeing used as protection for a carport, the car does not have to bemoved out of the carport before the screen can be raised or lowered.

STATE OF THE ART

There are circumstances in which the screen is required to interceptsunlight during extended periods when the sun is following its arc ofmovement across the sky. When the sun is approaching the two ends of itsmovement, protection from its rays ideally requires the screen to occupytwo mutually-transverse planes, respectively, both of which are inclinedwith respect to a vertical plane containing the track or tracks so thatone of the screens slopes upwardly from the common vertical plane whilethe second screen slopes downwardly from the vertical plane. For thescreen sloping downwardly from the vertical plane, the traveller islocated beneath the second of said pivotal axes. As long as thetraveller is located in this position, the stiffness of a frame,normally used to support the screen, provides a downwardly-inclinedstrut transmitting the weight of the screen downwardly and extendingbetween the screen and the traveller. The downward force acting throughthe strut resists the turning movement of the weight of the screen aboutthe upper end of the track and which urges the screen to flatten itselfagainst the track. The screen position can thus be accurately controlledby the position of the traveller as long as it is sloping down away fromthe common vertical plane.

However, if the screen is to slope upwardly away from the commonvertical plane the stiffness of the screen frame no longer provides aneffective strut opposing the turning moment referred to above. As aresult, an element of instability can occur in the ability of thetraveller to position the screen correctly. Such instability can easilycause collapse of the screen against the track, or damage its operatingmechanism, or even cause personal injury. For this reason theup-and-over non-folding screens currently proposed, only move the screenthrough about ninety degrees or less, from the lowered vertical positionto the raised horizontal position. As they only allow the screen to movethrough an angle not greater than about ninety degrees they avoid theabove-mentioned instability from occurring. For this reason theadvantage of having a screen moveable between two mutually transverseplanes and referred to above, is lost.

OBJECT OF THE INVENTION

An object of this invention is to provide an improved up-and-overscreen.

THE INVENTION

In accordance with the present invention an up-and-over screen assemblyhas at least one track for a traveller, a stably-supported screen fixedat one side to the traveller which is moveable up and down the trackrespectively to raise and lower the screen through more than ninetydegrees between a lowered upright position alongside the track and araised position at which the screen extends transversely from the trackto shield a chosen ground area adjacent the track from a particularambient condition, at least two rigid links rotating at their ends aboutparallel horizontal first and second pivotal axes to guide movement ofthe screen between its raised and lowered positions, the first pivotalaxis being fixed in relation to the upper end of the track and thesecond pivotal axis being fixed in relation to the screen, and, a devicepositionally fixed in relation to the screen assembly and for absorbingunwanted forces which would otherwise act on the traveller to cause thescreen to become unstable when raised through approximately ninetydegrees or more.

PREFERRED FEATURES OF THE INVENTION

In one arrangement the device provides a resilient bias that iscontrollable. The bias does not have to increase with the upwardmovement of the traveller close to the level of the second common axis.This may be achieved by having the device positioned above the travellerand suitably designed as a gas or hydraulic strut conveniently locatedin the upper end of the track so that it is engaged by the traveller asit approaches a position at which the screen is horizontal or nearly so.

In another screen assembly the device comprises a high ratiospeed-reduction gear box disposed between a drive unit which controlsthe position of the traveller on the track, and an inextensible driveloop connecting the traveller to the output side of the gear box. Theratio of the gearbox is sufficiently large, and it is of sufficientmechanical strength, to prevent the load on the drive loop reversing thedrive direction of the drive unit. Thus at all times the position of thetraveller is positively determined by the drive unit.

If the screen is of extended length it may be operated by two or moretravellers respectively moveable in synchronism along parallel uprighttracks.

In the preferred arrangement of the invention the screen assembly hastwo independently moveable screens respectively arranged one on eachside of two masts respectively providing two tracks. The masts may havepivotal connections arranged adjacent their upper ends and to which areattached the upper ends of two links respectively extending down to arespective screen. Each screen can be moved independently between astowage position at which it is arranged in a vertical or generalupright plane, alongside the masts, and an operating position at whichit extends transversely from the plane of the masts and slopes upwardsor downwards from the masts.

INTRODUCTION TO THE DRAWINGS

The invention will now be described in more detail, by way of an examplewith reference to the accompanying diagrammatic drawings, in which:

IN THE DRAWINGS

FIG. 1 shows in a perspective view a screen assembly having twoseparately-movable planar screens respectively gently sloping downwardlyaway from one another in order to shield a relatively large ground areafrom overhead conditions, such as rain or sun;

FIG. 2 is a view taken from one end of FIG. 1 and shows the right-handscreen positioned in a sloping plane substantially parallel to butspaced from another sloping plane containing the left-hand screen;

FIG. 3 shows the right-hand screen at a position it occupies duringmovement towards its stowage position when it lies in a vertical planeagainst two masts;

FIG. 4 shows to an enlarged scale and partly broken away, an end-view ofthe assembly with the right-hand screen shown in its stowage position,and the left-hand screen being elevated and being shown only in part,this figure showing in more detail the positions of components of theassembly used to guide movement of the screens and to locate them it intheir elevated and stowage positions;

FIG. 5 is a broken-away, detailed, explanatory vertical section of apart of FIG. 4 and shows a latch plate and associated stirrup used tohold a screen in its stowage position on one side of a mast, and a gasstrut which is compressed by vertical upward movement of a carriagealong the mast, the carriage being fixed to an associated traveller;and,

FIG. 6 is a cross-section through FIG. 5 taken on the line and in thedirection indicated by the arrows—VI-VI in FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 shows a screen assembly 1 comprising two spaced parallel masts2,3 having their lower ends set into a solid foundation and spacedapproximately three metres apart. Each mast comprises a centralcylindrical steel pole 4 having brackets 5 which attach to diametricallyopposite sides of the pole respective channel shaped guide rails 6 and7. The two masts 2,3 are attached at their upper-ends to a skeletalframework 10 (not shown in detail) which extends horizontally beneath acanvas canopy 8.

As shown in FIG. 6, each of the guide rails 6,7 is provided with anoutwardly-directed vertical slot 29 that leads into a channel 21 and isdefined between the opposed edges of two inwardly-directed lips 11provided at the entry to the channel. A roller carriage 9 shown in moredetail in FIG. 5 is mounted for vertical movement in an upright trackthe channel 21 of each of the guide rails 6,7. An attachment plate 28fixed to the carriage 9 extends through the slot 29 in the guide railand provides part of a traveller 26. The end of the plate 28 protrudesfrom the slot 29 and is held between the arms of a clevis 12 which ispivoted to the plate by a horizontal pin 13.

Referring back to FIG. 1, the screen assembly 1 shields the ground areabeneath it from ambient conditions, by means of two screens 14,15. Eachscreen comprises a strong rectangular light tubular metal frame 16reinforced on its upper surface as shown in FIG. 1, by a pair ofhorizontal tubular, stiffening bars 19. Further stiffening is providedby three spaced parallel metal pipes 17, attached to the frame 16 bysuitably-shaped brackets (not shown). As shown in FIG. 1 the twooutermost pipes 17 carry fixtures 18 on their upper surface intermediatetheir ends for the attachment of the lower ends of pivotal links 22,23.

The frame 16 is spanned by an air-permeable thin layer of thin parallelreeds or canes 20 which gives protection from the sun above. The canesare attached at their ends to the frame 16. Horizontally extending thin,overlapping sheets of pliant polycarbonate (not shown) may be attachedto the upper surface of each of the screens 14,15 to prevent waterpassing through them. The overlap of the sheets and the permeable natureof the reed or cane layer, allow air to flow upwardly through the screenso that any differential air pressure which might otherwise cause thescreens to lift bodily, is dissipated before damage to the assembly canoccur. Additionally the space beneath the screen remains cool as hot aircan convect upwardly through the cane or reed layer.

Movement of each of the screens 14, 15 to its different operatingpositions is guided in part by one of the pairs of parallel rigid links22, 23. These links are each pivoted at their respective ends toparallel horizontal pivotal axes. The links 22,23 are attached at theirupper-ends to the skeletal framework 10 at positions directly above thecentre lines of the poles 4 of the respective masts 2,3. The upperpivotal axes for the links 22, 23 are provided by respective co-axialpivot bolts 24 extending horizontally as is clearly shown in FIG. 4.

The lower ends of the links 22, 23 are respectively connected to the twoattachments 18 provided on the outermost stiffening pipes 17 of eachscreen as shown in FIGS. 1 and 3. These attachments provide coaxialpivotal points to which the lower ends of the links 22 and 23 areconnected. The links of each screen always move in synchronism andparallel to one another.

Vertical movement of the travellers 26 controls the vertical positioningof the screens 14,15. As shown in FIG. 4, the travellers 26 are liftedby inextensible cables 30 which are attached at their lower ends to thetraveller 26. The upper-ends of the cables 30 are coiled around one oftwo, axially parallel, cylindrical pulleys 31 located beneath the canopy8 as shown in FIG. 4. The two cylindrical pulleys 31 each carry ataxially spaced positions the convolutions of the cables 30 of one of thescreens 14, 15 and can be independently rotated by their own drivemotors (not shown). As the pulleys 31 are identical, rotation of eitherof them causes the two cables 30 associated with them to move insynchronism and alter the positions of the two travellers 26 of theassociated screens.

In the example being described, the direction of rotation of theelectric motors controlling the rotation of a corresponding pairs ofpulleys 31, is remotely controlled by a hand-operated unit (not shown)that is provided with the screen assembly. However, the use of anelectric motor to control the rotation of a pair of pulleys may bereplaced by a manual drive, if preferred.

A horizontally-extending rectangular stirrup 40 of stiff wire shown inFIGS. 5 and 6 is provided towards the upper-end of each of the masts 2,3as shown in FIG. 4, the loop of the stirrup extending horizontallytowards the upper portions of the respective screens 14,15 when in theirstowage positions. Each screen is provided with two latch plates 41 asshown in FIGS. 4 and 5 which are respectively fixed to the outer ends ofthe outermost of the stiffening pipes 17 on each screen. The latch plate41 is shaped to provide a claw 42 which latches over the associatedstirrup 40 when the associated screen is in its vertical stowageposition as shown in the right-hand portion of FIG. 5. The claw 42 formsthe upper-end of an entry slot 43 on the latch plate 41 and the stirrup40 is guided into the slot 43 as the screen approaches its stowageposition, by upper and lower ramp surfaces 44, 45 which respectivelylead into the slot 43. The final descent of the screen to its verticalstowage position during lowering, involves a turning movement of theupper-part of the screen towards the masts 2, 3, and a lowering movementof the screen caused by downward movement of its two travellers 26. Theparts are so arranged with respect to one another that during this finaldescent of the screen, the entry slots 43 of its two latch plates 41assume a horizontal position directly opposite the associated stirrups40. The turning movement of the screen about the lower ends of the links22, 23 causes the stirrups 40 to enter the slots 43 and to assumepositions beyond the down-turned ends of the claws 42. The terminal partof the descent of the screen causes the stirrup 40 to latch behind theclaw 42 and thus retain the screen in a position at which it lies in aplane parallel to the vertical plane containing the two masts 2,3, asillustrated in FIG. 4. The links 22, 23 slope downwardly towards thescreen from their upper-ends so that, during subsequent lifting of thescreen by the two associated travellers 26, the latch plate entry slots43 are first raised to the level of the stirrups 40 and the increasinginclination of the two links 22, 23 away from the vertical, togetherwith the inclination of the ramp surface 45, forces the upper-endportion of the screen outwardly about the lower ends of the links 22,23.Simultaneously the latch plates 41 disengage from their respectivestirrups 40. Further lifting of the screen can then take place to alterits plane from a vertical position alongside the masts 2,3 to ahorizontal position at which the screen extends approximately at rightangles from the upper-end portions of the masts 2, 3 as shown in FIG. 1.

As is shown in FIGS. 5 and 6 a vertical gas strut 60 is provided insidethe upper-end portion of each of the guide rails 6 and 7 and isadjustable to provide a desired compressive resistance. A piston 61 ofthe strut 60 extends downwardly and terminates in a head 62 which isengaged by the carriage 9 of the associated traveller 26 when the screenis lifted towards a position at which it is almost horizontal. Suchengagement occurs immediately prior to the screen becoming horizontal,and thus the lifting force of the traveller 26 by the associated cable30 encounters an additional resistance generated by the gas strut 60, asthe carriage 9 approaches the upper-end of its movement. The resistancecreated by the gradual upward compression of the strut 60 prevents anytendency of the screen to collapse uncontrollably against the masts 2,3.The increase in the resistance offered by the gas strut 60 is chosen tomatch the reduction in load on the cable 30 as the screen moves upwardsto and through the horizontal position. The load on the cable 30 is thusmaintained sensibly constant and the cable is, of course, made from aninextensible material. The struts 60 thus enable each screen 14, 15 tomove between elevated positions it slopes upwardly or downwardly fromthe masts 2,3 without loss of control. The two screens can thus bearranged to provide a larger and more effective area of protection fromabove against sunlight or rain, than can be achieved by a single screenof similar area.

Modifications of the Preferred Embodiment

Various modifications to the above-described example of the inventionare possible. For example, the gas strut may be replaced by a mechanicalspring mounted inside an enclosure attached to either the upper or lowerend of each mast. The spring is then arranged to introduce a thrustduring terminal part of the lifting of the associated traveller to aposition at which the screen is nearly horizontal. The mechanicaltensioning (or compression) of the spring is chosen to compensate forthe reduction in downward forces on the travellers which occur when thescreen passes through its horizontal elevated position and which wouldotherwise cause the positioning of the screens 14, 15 to becomeunstable.

In a further modification, the cable 30 is replaced by an inextensibleloop made, for example, from a Reynolds chain, which is connected at itstwo ends to a traveller and passes around gear wheels at the upper andlower ends of the associated track. One of the two gear wheels is drivenby an electric motor or manually, by way of a high-ratio drivetransmission mechanism such as a gearbox or a leadscrew. The high ratiois so chosen that it is incapable of transmitting drive in the reversedirection. Thus the drive applied to the driven gear wheel preciselycontrols the position of the associated traveller as it moves up anddown the track and travels through the zone where instability wouldotherwise occur.

Although the example of the invention shown in the drawings describes indetail two independently moveable screens, the invention is equallyapplicable to a single screen supported by two or more travellersrunning along respective upright parallel upright tracks, and inparticular to a pair of screens of extended length arranged alongside apath on the ground which is to be protected from overhead ambientconditions such as sunlight or rain. When the screens are lowered intothe vertical plane, they provide privacy between opposite sides of thescreens. By raising the screens to their vertical positions they can beused to protect the areas beneath them from overhead inclement weatherconditions. Such an arrangement is particularly well-suited to anoutdoor restaurant where the screens can be mounted on masts arranged ina line passing between two rows of tables.

In some situations, it is required to use a screen of the invention toprotect a path extending alongside a wall, from adverse weatherconditions. A typical use is in conjunction with a carport. The uprightparallel guide rails providing tracks along which the travellers of thescreen move, are suitably vertically set into the wall at spacedintervals. The stowage position of the screen is then vertical,alongside the wall. Lifting of the screen to a horizontal positionresults in it extending above the carport to provide overhead protectionfor a car standing in the carport. Such movement does not require thecar to be driven from the carport before it can take place.

A further usage of a two-screen assembly as shown in the example of theinvention specifically described above is to provide a cabana-typestructure. One of the two screens can be arranged horizontally toprovide a roof to the cabana and the other screen can be arranged in itsverticalstowage position at which it provides a back wall to the cabana.One can envisage such a use of the invention as being particularlyappropriate in the vicinity of a private swimming pool when it willprovide shade from above and privacy from behind. The direction ofopening of the cabana can be easily changed, if a wind reversal occurs,by interchanging the vertical and horizontal positioning of the screens.

1-10. (canceled)
 11. An up-and-over screen assembly having at least oneupright track for a traveller, a stably-supported screen fixed at oneside to the traveller which is moveable up and down the trackrespectively to raise and lower the screen through ninety degrees ormore between a lowered upright position alongside the track and a raisedposition at which the screen extends transversely from the track toshield a chosen ground area adjacent the track from a particular ambientcondition, at least two rigid links rotating at their ends aboutparallel horizontal first and second pivotal axes to guide movement ofthe screen between its raised and lowered positions, the first pivotalaxis being fixed in relation to the upper-end of the track and thesecond pivotal axis being fixed in relation to the screen, and, a devicepositionally fixed in relation to the screen assembly and for absorbingunwanted forces which would otherwise act on the traveller to cause thescreen to become unstable when raised through approximately 90 degreesor more.
 12. An assembly as claimed in claim 11, in which the deviceprovides a resilient bias.
 13. A screen assembly as claimed in claim 12,in which the resilient bias is adjustable and provided by a gas strut.14. An assembly as claimed in claim 13, in which the gas strut isassociated with a track containing a carriage having a part whichextends laterally from the track to provide the lower end of a travellerwhich is pivotally attached to a lower part of the screen.
 15. Anassembly as claimed in claim 11, in which a drive-transmission mechanismis mounted between a drive source and a pulley controlling the tensionof an inextensible cable loop which controls the position of thetraveller on the track, the drive transmission mechanism having a driveratio which is sufficiently large to prevent the reversal of drivethrough it so that unwanted forces which might otherwise render thescreen unstable when in its elevated position are absorbed.
 16. Anassembly as claimed in claim 11, in which an electric motor is used tomove the traveller up and down the track.
 17. An assembly as claimed inclaim 11, in which a latch mechanism having one component on the screenand a second component fixed in relation to the track is engaged whenthe screen is moved towards an upright stowage position alongside thetrack, the latch mechanism being effective to positively locate an upperend-portion of the screen at a position alongside the track, and thepivotal axis at the upper-end of the link associated with the screenbeing positioned nearer the track with respect to the pivotal axis atthe lower end of the link to ensure that the link slopes downwardlyslightly away from the track when the screen is in its vertical stowageposition.
 18. An assembly as claimed in claim 17, in which two screensare respectively provided at opposite sides of spaced parallel verticalmasts and are independently moveable by drives provided on a structureinterconnecting the upper-ends of the masts, the masts providing attheir upper-ends respective horizontal coaxial pivot axes lying in thesame plane as the masts and on each of which are pivoted the upper-endsof a pair of rigid links which extend divergently downwardly torespective screens.
 19. An assembly as claimed in claim 11, in which thescreen is supported by travellers respectively arranged in a line ofspaced upright parallel tracks mounted on a wall, each traveller beenprovided with its own device and being vertically positioned on itstrack by a cable, a drive common to the cables being used to move thetravellers in synchronism along their respective tracks.
 20. An assemblyas claimed in claim 11, in which the track is provided by the interiorof a vertically slotted guide attached to one side of a pole and asecond guide providing a second track is attached to the opposite sideof the pole, each track having its own traveller fixed to one edge of arespective screen.